Follow these simple steps to assemble your delicious Spinach and Mushroom Toast. The process is straightforward, focusing on building layers of flavor.

1. Prepare the Mushrooms: Heat 1 tablespoon of olive oil in a large skillet or pan over medium-high heat. Once the oil is shimmering, add the sliced mushrooms in a single layer. Avoid overcrowding the pan; cook in batches if necessary. Cook for 5-7 minutes, stirring occasionally, until they are nicely browned and have released their moisture. This browning process is key to developing their deep, umami flavor. Once browned, remove the mushrooms from the skillet and set them aside on a plate.
2. Sauté Aromatics and Wilt Spinach: Reduce the heat to medium. Add the remaining 1 tablespoon of olive oil to the same skillet. Add the minced garlic and cook for about 30-60 seconds until fragrant. Be careful not to burn the garlic, as it can become bitter. Immediately add the fresh spinach to the skillet. It might seem like a lot, but it will wilt down significantly. Stir gently and continuously until the spinach has wilted, which should take about 2-3 minutes. If using larger spinach leaves, you might want to roughly chop them beforehand.
3. Combine and Create the Creamy Topping: Return the cooked mushrooms to the skillet with the wilted spinach. Stir to combine. Now, add the heavy cream (or softened cream cheese). Stir until the cream has warmed through and slightly thickened, coating the spinach and mushrooms beautifully. If using cream cheese, stir until it has melted and combined into a creamy sauce.
4. Season and Flavor: Stir in the freshly grated Parmesan cheese. Season the mixture generously with salt and freshly ground black pepper to your taste. If you enjoy a little heat, add a pinch of red pepper flakes. For a touch of brightness, stir in the optional lemon zest at this stage. Taste and adjust seasonings as needed. Keep the mixture warm over low heat while you prepare the toast.
5. Toast the Bread: While the spinach and mushroom mixture is simmering gently, toast your bread slices until they are golden brown and delightfully crispy. You can do this in a toaster, under a broiler (watch carefully to prevent burning!), or on a grill pan for lovely char marks. If desired, you can rub a cut garlic clove over the warm toast for an extra layer of garlic flavor, or lightly drizzle it with olive oil.
6. Assemble Your Masterpiece: Place the toasted bread slices on individual plates. Generously spoon the warm, creamy spinach and mushroom mixture over each slice of toast.
7. Garnish and Serve: If desired, garnish with an extra sprinkle of freshly grated Parmesan cheese, a pinch more red pepper flakes, or some fresh herbs like chopped parsley or chives. Serve immediately while the toast is crisp and the topping is warm and inviting.